1. Field of Invention
The present invention pertains to the field of vehicle trailers. More particularly, this invention is related to a trailer hitch configured to selectively tilt relative to the towing vehicle in order to reduce an angle of incline between a loading ramp and each of the trailer deck and the surface on or from which the trailered vehicle is being unloaded or loaded.
2. Description of the Related Art
In the field of towing, it is well known that trailers are often used to transport vehicles of various types and sizes. Transported vehicles, such as automobiles, construction equipment and military equipment, roll on and off the loading end of the trailer. Typically, ramps are used to roll equipment or automobiles up the short height. The ramps are installed between the trailer deck and the ground or other surface onto which the vehicle is to be unloaded or from which the vehicle is being unloaded. An obtuse angle is defined between the ramps and the trailer deck. Similarly, an acute angle is defined between the ramps and the ground.
When the vehicle is being loaded or unloaded, the acute angle at the bottom of the ramp often creates a clearance problem between the vehicle and the trailer. For a vehicle being driven forward onto the trailer, the clearance problem exists between the front end of the vehicle and the ramp. Further, the obtuse angle at the top of the ramp creates a clearance problem between the portion of the vehicle between the axles and the loading end of the trailer. For vehicles such as “low riders” which have a ground clearance of only a few inches, the interference between the vehicle and the ramps or the ground are more profound. For vehicles such as construction equipment and military vehicles which include endless loop belt drives, the vehicle is loaded or unloaded slowly until an equilibrium point is surpassed and the vehicle tilts in an opposing direction. Specifically, when a tank, for example, is being loaded onto a trailer, the front end of the tank extends into the air above the trailer until the tank is advanced far enough onto the ramps such that the center of mass is above the top of the ramps. After this point, the tank pivots and “lands” on the trailer. When unloading, this “landing” takes place on either the ramps or the ground. In each situation, the loading and unloading of such equipment is to some extent uncontrolled.
Various configurations of ramps have been devised to assist in loading and unloading vehicles on and off trailers. Additionally, various complex mechanical devices have been devised to be carried the vehicle or the trailer to assist in tilting the trailer in order to reduce the respective angles between the trailer, the ramp and the ground. Various of these devices are provided for eliminating the ramps altogether.
Typical of the art are those devices disclosed in the following U.S. Patents:
U.S. Pat. No.Inventor(s)Issue Date3,891,239J. D. Leo et al.Jun. 24, 19754,570,966G. W. Giboney et al.Feb. 18, 19864,929,028L. A. UnderwoodMay 29, 19904,946,182R. WeberAug. 7, 19906,155,588V. MaxeyDec. 5, 20006,726,237T. J. CarricoApr. 27, 2004
Of these patents, the '239 patent issued to Leo et al., discloses a tractor truck having a pivoting frame extending from the rear. The frame includes a lateral member on which is provided a laterally adjustable hitching ball. The frame is vertically adjustable via hydraulic actuators.
Giboney et al., in the '966 patent, disclose a retractable hitch ball for “gooseneck” type trailers. The hitch ball is housed within a self-contained unit beneath the bed of a towing vehicle. A hydraulic cylinder is operated from within the towing vehicle for moving an elevating block relative to a pivoted lifting plate which is biased downwardly by a spring. The hitch ball is elevated and lowered vertically through an opening in the towing vehicle to active and inactive positions.
The '028 patent issued to Underwood discloses a hitch apparatus having a movable structure configured for selectively tilting a trailer with respect to the vehicle so as to facilitate loading and unloading equipment, automobiles, materials, onto or off of the trailer. The hitch apparatus includes an elongated chamber-like structure that has an open top and an interior which is in communication with the open top. The chamber-like structure is sized and configured in the manner of a conventional pickup truck bumper. The apparatus further includes a ball hitch movably connected to a trailer. The ball hitch is mounted for movement with respect to the chamber-like structure, so that the combination hitch connection may be selectively positioned through the use of extendable members. The ball hitch may be moved between a lowered position adjacent the chamber-like structure and a raised position above the chamber-like structure.
Weber, in the '182 patent, discloses a towing hitch which includes three or more power cylinders to effect adjustment of the hitch along a central axis in horizontal and vertical directions to accommodate road or site conditions. The hitch may also be used as a rear end jack for the towing vehicle to provide access to the rear tires.
In his '588 patent, Maxey discloses a tilting trailer hitch including a compressible main support assembly having a hitch coupler and a hitching mechanism. The hitch coupler is configured to connect a towing connector to a towing vehicle and the hitching mechanism is configured to couple with a trailer. An actuator is pivotally connected to the main support assembly in response to trailer loading and is operable to rotate part of the main support assembly, thereby raising or lowering the hitching mechanism along a generally arcuate path. When the hitching mechanism is in the raised position, a loading end of the trailer is lowered to assist in loading the trailer.
The '237 patent issued to Carrico discloses a vertically operable hitch including a horizontal support member having a forward end journaled in the receiver of a tow vehicle. An upright post on the support member has a carrier operably mounted thereon for selective vertical movement along the post. A hitch ball is mounted on the carrier for selective connection to the tongue of a towed trailer to thereby selectively raise and lower the hitch ball.